Last year marked the highest global temperature on record - 0.84°C (or 1.51°F for our American friends) above the 20th-century average. While the environment has been slowly heating up since 1880, the average rate of this increase has more than doubled since 1981 — which has led to the last six years being the hottest on record. Normally, the Earth’s temperature fluctuates a few degrees between temperature extremes, so this consistent, unbroken string of hot years is proving a concern.
The heating of the Earth has also resulted in another extreme event, which we touched on in last month’s column. A rise in temperatures means an increased demand for oxygen and a decreasing production rate. This unequal exchange is most noticeable in the ocean, where the rising heat could disrupt the oxygen production of phytoplankton, which produces nearly two-thirds of the world’s oxygen supply.
The critical tipping point for is at 6°C (or 10.8°F) above Earth's normal, after which we may experience a runaway greenhouse effect. At this stage, existing climate conditions will be enough to continue to heat the Earth indefinitely. The UN’s goal is to limit this change as much as possible over the next century, allowing developed and developing nations alike to switch to more renewable energy sources and limit waste material products such as plastic.
However, the exact effect on ocean lifeforms is still largely unknown. Using modelling that reproduces the closest event in Earth’s history (the end-Permian mass extinction of 250 million years ago), it's estimated that this will result in widespread death. Already the world’s coral reefs, which harbour at least 25% of marine life, are dying off due to global warming, disturbing the delicate algae that reefs rely on for food. The death of these reefs is known as ‘coral bleaching' and may mean the death of 70-90% of reefs by 2050 unless global temperatures can be limited to 1.5°C.
So, whatever benchmark we choose, the line we walk this decade is tight.
Sources: Science, The Weather Channel
About the author - meet Earthan James McCulloch
James is a literary student and environmental enthusiast who likes thinking about the better futures we could have (and those we best avoid). When not playing with other people’s dogs or taking long, mindful walks, he’s usually found reading and writing, often at the local library. You can check him out on his blog for something a little different, where he talks about all things literary or otherwise.